We propose to design, construct, evaluate, and operate an area x-ray diffractometer system as a "national resource". It now requires about 400 hours of continuous exposure to record with a diffractometer the diffraction data from a typical protein crystal. We anticipate being able to record data of similar quality in 20 hours. The system would consist of an x-ray source, graphite monochromator, crystal goniometer, helium chamber, xenon filled multiwire proportional chamber, associated readout system controller, local memory and minicomputer. The output data for the user would be a magnetic tape listing of structure factor amplitudes.